[AMPS] parasitic suppressors

[Ian White, G3SEK]

Rich Measures wrote:

>
>>Agreed that 1N540x diodes will usually work, but their 200A surge rating
>>is strictly time-limited... and we don't actually know how long the
>>surge will last. 
>
>sure we do.  T=R*C.

That isn't the dominant time constant in a near-crowbar short. If the
arc voltage is about 50V and the current is about 50A, R is on the order
of one ohm, so R*C is a few tens of microseconds. 

Therefore the dominant time-constant is the delay until the mains or HV
fuse blows (or the breaker operates). That's about a thousand times
longer than R*C. Until then, the HV transformer is still powering the
current surge.


... <snip - nothing else worth disagreeing about>

73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.demon.co.uk/g3sek

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